Fuel injection type rotary piston engine

ABSTRACT

Fuel injection type rotary piston engine having side air intake ports formed in the side housings and peripheral air intake port or ports formed in the rotor housing, said side air intake ports being closed during light load or low speed operation of the engine while the peripheral air intake ports are still open, the peripheral ports having an effective passage area which is small in relation to that of the side ports.

The present invention relates to a rotary piston type internalcombustion engine, and more particularly to a rotary piston type engineof such a type that includes a casing which comprises a rotor housinghaving a trochoidal inner wall surface and a pair of side housingssecured to the opposite sides of the rotor housing, and a substantiallypolygonal rotor disposed in said casing for revolution and rotation withapices thereof in sliding contact with the trochoidal inner wall so asto define working chambers in the casing.

It has already been proposed in this field of art to provide a fuelinjection type rotary piston engine having air intake port means formedin one of the side housings and auxiliary air intake port means formedin the rotor housing. In the known arrangement, air is taken into theworking chamber through both of the air intake port means throughout theengine operation. Therefore, during light load or low speed operation ofthe engine, fresh air taken into the working chamber is made turbulentso that it becomes very difficult to obtain fuel-air mixture ofstratified condition.

The present invention therefore has an object to provide a fuelinjection type rotary piston engine having means for preventing intakeair from becoming turbulent during light load or low speed operation ofthe engine.

Another object of the present invention is to provide a fuel injectiontype rotary piston engine in which fuel-air mixture of stratifiedcondition can readily be formed in the working chamber during light loador low speed operation of the engine.

According to the present invention, there is provided a fuel injectiontype rotary piston engine including a rotor casing which comprises arotor housing having a trochoidal inner wall and a pair of side housingssecured to the opposite sides of the rotor housing to define a rotorchamber therein, a substantially polygonal rotor disposed in said rotorchamber for revolution and rotation therein with apices thereof insliding contact with said trochoidal inner wall of the rotor housing soas to define working chambers between the casing and the rotor, firstair intake port means formed in at least one of said side housings so asto open into the rotor chamber, first air intake passage meanscommunicating with said first air intake port means and having firstthrottle valve means disposed therein, second air intake port meansformed in said rotor housing so as to open into the rotor chamber,second air intake passage means communicating with said second airintake port means and having second throttle valve means disposedtherein, means for closing said first throttle valve means in said firstair intake passage means during light load operation of the engine whilethe second throttle valve of said second air intake passage means isstill open, and fuel injection means for fuel into one of the workingchambers into which fresh air is introduced. Hithertofore, it has beenrecognized that an air intake port formed in the side housing isparticularly suitable for light load or low speed operation since theoverlapping period can be minimized and that a peripheral air intakeport formed in the rotor housing is particularly suitable for heavyloador high speed operation because it can provide an increased air intakeefficiency although there may be relatively large overlapping period.The invention, however, proposes to use only the peripheral air intakeport means during light load or low speed engine operation in order toobtain a better atomization of fuel, and a fuel-air mixture of laminatedcondition. Therefore, according to a preferred mode of the presentinvention, the effective cross-sectional area of the peripheral orsecond intake port means is small as compared with that of the side orfirst air intake port means with preferable range of the ratio of theareas between 1 to 3 and 1 to 69, so that the overlapping period of thesecond air intake port means can be minimized.

The above and other objects and features of the present invention willbecome apparent from the following descriptions of preferred embodimentstaking reference to the accompanying drawings, in which:

FIG. 1 is a sectional view of a rotary piston engine in accordance withone embodiment of the present invention;

FIG. 2 is a sectional view similar to FIG. 1 but showing anotherembodiment of the present invention; and

FIG. 3 is a sectional view taken substantially along the line III--IIIin FIG. 2.

Referring now to the drawings, particularly to FIG. 1, there is shown arotary piston type engine including a casing 1 which comprises a rotorhousing 2 having a trochoidal inner wall 2a, and a pair of side housings3 secured to the opposite sides of the rotor housing 2 so as to define arotor chamber 1a in the casing 1. A substantially triangular rotor 4 isdisposed in the rotor chamber 1a and has apex seals 4a provided on theapices thereof for slidable sealing contact with the inner wall 2a ofthe rotor housing 2 so as to define working chambers C1, C2 and C3 inthe casing 1, of which volumes are continuously changed as the rotor 4rotates. In the illustrated position of the rotor 4, the working chamberC1 is in the intake stroke, the chamber C2 in the compression stroke andthe chamber C3 in the expansion and exhaust stroke.

The rotor housing 2 of the casing 1 is formed with a peripheral airintake port 5 opening into the rotor chamber 1a at the working chamberC1 which is in the intake stroke. Further, the rotor housing 2 isprovided with a fuel injection nozzle 6 for injecting nozzle into theworking chamber C1. At least one of the side housings 3 is provided witha side air intake port 7 opening to the rotor chamber 1A at the workingchamber C1 which is in the intake stroke. The intake ports 5 and 7respectively communicate with intake passages 8 and 9 which extendbetween an air cleaner 10 and the intake ports 5 and 7. The passages 8and 9 are provided with throttle valves 11 and 12, respectively, whichare simultaneously actuated by suitable means (not shown) well known inthe art.

The peripheral intake port 5 has an effective passage area which issmall in relation to that of the side intake port 7 or the ports 7 whenthey are formed in both of the side housings 3. Preferable ratio of theeffective passage area of the port 5 to that of the port 7 is between 1to 3 and 1 to 9. The term "effective passage area" as used herein willmean the minimum passage area of the whole passage including the intakeport itself and the intake passage portion. The throttle valves 11 and12 are interconnected with each other and, as shown in FIG. 1, thethrottle valve 11 remains slightly open when the throttle valve 12 iscompletely closed.

The rotor housing 2 is also provided with ignition plugs asschematically shown by 13 and also with an exhaust port 14. Thereference numeral 15 designates an output shaft of the engine.

During light load or low speed operation of the engine, the throttlevalve 12 is closed while the throttle valve 11 remains slightly open asshown in FIG. 1 so that fresh air is taken only through the intakepassage 8 and the peripheral intake port 5 into the working chamber C1which is in the intake stroke. Since the peripheral intake port 5 has areduced effective passage area as previously described, a stable intakeair flow of substantial speed can be assured in the working chamber C₁.At a suitable period of operation cycle, fuel is injected through thenozzle 6 into the intake air flow in the working chamber C₁ whereby thefuel is atomized and mixed with the air to form a fuel-air mixture.Since the intake air is introduced into the working chamber C₁ with asubstantial flow speed, it is possible to form relatively rich mixtureat a portion of the working chamber and relatively lean mixture and/orair at the remaining portion of the chamber. Thus, it is possible tomake the mixture in the working chamber into a laminated condition, andthe mixture is ignited by the ignition plugs 13 at the rich portionthereof. Since the peripheral intake port is of a reduced area, it ispossible to decrease the overlap period, so that possibility of intakeair being diluted by combustion gas can be substantially decreased.

In the illustrated structure, the peripheral air intake port 5 isconstituted by a single port opening, however, it should be noted thatthe port 5 may be divided into a plurality of small holes.

Under a high speed and high load operation of engine, the throttle valve12 is opened and air is allowed to flow through the intake passage 9into the working chamber C₁. Thus, increased amount of air is suppliedto the working chamber C₁ to provide an increased engine output.

Another embodiment of the present invention is shown in FIGS. 2 and 3.The engine shown in these drawings is substantially the same as thatshown in FIG. 1, so that detailed descriptions of its structure andfunction will not be repeated. Further, corresponding parts in theembodiment in FIGS. 2 and 3 are designated by the same referencenumerals as in FIG. 1 with addition of 100.

In this embodiment, the peripheral air intake port 105 formed in therotor housing 102 is provided with a valve 17 which is rotatablyreceived in the rotor housing 102 and has an actuating lever 16 securedto one end thereof. As shown in FIG. 3, the intake port 105 is dividedinto three holes 105a, 105b and 105c, and the valve 17 also has passages17a, 17b and 17c which respectively cooperate with the holes 105a, 105band 105c of the intake port 105. In the drawing, the passages 17a and17c are shown in the form of transversely extending through-holes andthe passage 17b is shown as a circumferential groove.

According to this alternative embodiment of the present invention, it ispossible to control the flow speed and amount of intake air through theintake port 105 by changing the position of the valve 17.

The invention has thus been shown and described with respect topreferred embodiments, however, it should be noted that the invention isin no way limited to the details of the illustrated structure butchanges and modifications may be made without departing from the scopeof the appended claims.

I claim:
 1. A rotary piston type internal combustion engine comprising acasing including a rotor housing having a trochoidal inner peripheralwall and a pair of side housings secured to the opposite sides of saidrotor housing to define a rotor chamber therein, a substantiallypolygonal rotor rotatably mounted in said rotor chamber and havingapices slidingly contacting the trochoidal inner peripheral wall of therotor housing so as to define working chambers between the casing andthe rotor, means for rotating the rotor so as to effect volumeticchanges of each working chamber through intake, compression, combustionand exhaust strokes, first air intake port means formed in at least oneof said side housings so as to open into the working chamber which is inthe intake stroke, first air intake passage means communicating withsaid first air intake port means and having first throttle valve meanspositioned therein, second air intake port means formed in said rotorhousing so as to open into the working chamber which is in the intakestroke, second air intake passage means communicating with said secondair intake port means and having second throttle valve means positionedtherein, means for closing said first throttle valve means in said firstair intake passage means during light load operation of the engine whilekeeping the second throttle valve of said second air intake passagemeans open, and fuel injection means for injecting fuel into the workingchamber which is in the intake stroke.
 2. Rotary piston engine inaccordance with claim 1 in which said second air intake port meanscomprises a single intake port.
 3. Rotary piston engine in accordancewith claim 1 in which said second air intake port means comprises aplurality of small holes.
 4. Rotary piston engine in accordance withclaim 1 in which said second air intake port means has an effectivepassage area smaller than that of the first air intake passage means. 5.Rotary piston engine in accordance with claim 4 in which the ratio ofthe effective passage area of the second air intake port means to thatof the first air intake port means is between 1 to 3 and 1 to
 9. 6.Rotary piston engine in accordance with claim 1 in which said second airintake passage means is provided with valve means for controlling thepassage area thereof. .Iadd.
 7. A rotary piston type internal combustionengine comprising a casing including a rotor housing having a trochoidalinner peripheral wall and a pair of side housings secured to theopposite sides of said rotor housing to define a rotor chamber therein,a substantially polygonal rotor rotatably mounted in said rotor chamberand having apices slidably contacting the trochoidal inner peripheralwall of the rotor housing so as to define working chambers between thecasing and the rotor, means for rotating the rotor so as to effectvolumetric changes of each working chamber through intake, compression,combustion and exhaust strokes, first fluid intake port means formed inat least one of said side housings so as to open into the workingchamber which is in the intake stroke, first fluid intake passage meanscommunicating with said first fluid intake port means and having firstthrottle valve means positioned therein, second fluid intake port meansformed in said rotor housing so as to open into the working chamberwhich is in the intake stroke, second fluid intake passage meanscommunicating with said second fluid intake port means and having secondthrottle valve means positioned therein, means for closing said firstthrottle valve means in said first fluid intake passage means duringlight load operation of the engine while keeping the second throttlevalve of said second fluid intake passage means open and means forintroducing fuel into the working chamber during the intake stroke..Iaddend. .Iadd.
 8. Rotary piston engine in accordance with claim 7 inwhich said second fluid intake port means comprises a single intakeport. .Iaddend. .Iadd.
 9. Rotary piston engine in accordance with claim7 in which said second fluid intake port means comprises a plurality ofsmall holes. .Iaddend. .Iadd.
 10. Rotary piston engine in accordancewith claim 7 in which said second fluid intake port means has aneffective passage area smaller than that of the first fluid intakepassage means. .Iaddend. .Iadd.
 11. Rotary piston engine in accordancewith claim 7 in which the ratio of the effective passage area of thesecond fluid intake port means to that of the first fluid intake portmeans is between 1 to 3 and 1 to
 9. .Iaddend. .Iadd.
 12. Rotary pistonengine in accordance with claim 7 in which said second fluid intakepassage means is provided with valve means for controlling the passagearea thereof. .Iaddend.